600 500 ◆Storable Biprop 400 Cryo -Electric 岂 x-Nuclear 300 ◇Biprop GEO tug ▣Cryo GEO tug 200 o Electric GEO tug ▲Electric GEO cruiser 100 0 0 0.2 0.4 0.6 0.8 Utility(dimensionless) Fig.9.Low capability systems,showing effect of increasing fuel load,with GEO rescue vehicles ICE design sessions typically last several hours and to develop a point design.Finally,cost was estimated usually address one major trade per design session.A during the post-processing segment. senior team member,or "facilitator,"leads the design sessions and helps to resolve disconnects between the Ten ICEMaker modules were developed,with each clients.The design sessions are iterative,with each module representing a different spacecraft subsystem or subsystem sending and receiving many times in order discipline.The six main modules were Mission, for the point design to converge.Although it has Systems,Propulsion,Link,Configuration,and Power. recently become possible to automate this iterative Each sheet performed all the calculations necessary to process,human operation of the client stations is almost design its specific subsystem based on the inputs always preferred.The human element is actually key to provided to it.The models were developed using first the method.The human expert can guide the iterations. principles whenever possible,but rules-of-thumb based catching bugs,nonsensical answers,divergence,and on current technology were also used to reduce other pathologies that complex computational systems complexity and coding time.These sheets were are prone to.More importantly,the experts make major electronically linked through the ICEMaker server and discontinuous design decisions,or go"outside the box' interacted throughout a design session sharing by stretching parameter ranges or even adding new information and updating each other of changes to the computational capabilities,making the ICE method a design made by the individual chairs.The ICEMaker true design tool,not just a non-linear equation solver. server works primarily with Microsoft Excel spreadsheets.This work also made innovative use of a ICE Model new software tool (Oculus CO)that was used to link Each session was broken down into three segments: routines written in Mathworks Matlab and a pre-processing,design,and post-processing.Customer parametric solid geometry model done in Solidworks inputs,payload design,and mission objectives were to the spreadsheets. decided by an Architecture chair during pre-processing These inputs were fed to the design team and were used Several key simplifying assumptions were made.First the sheets were only required to handle one vehicle per 7 American Institute of Aeronautics and Astronautics7 American Institute of Aeronautics and Astronautics 0 100 200 300 400 500 600 0 0.2 0.4 0.6 0.8 1 Utility (dimensionless) Cost (M$) Storable Biprop Cryo Electric Nuclear Biprop GEO tug Cryo GEO tug Electric GEO tug Electric GEO cruiser Fig. 9. Low capability systems, showing effect of increasing fuel load, with GEO rescue vehicles ICE design sessions typically last several hours and usually address one major trade per design session. A senior team member, or “facilitator,” leads the design sessions and helps to resolve disconnects between the clients. The design sessions are iterative, with each subsystem sending and receiving many times in order for the point design to converge. Although it has recently become possible to automate this iterative process, human operation of the client stations is almost always preferred. The human element is actually key to the method. The human expert can guide the iterations, catching bugs, nonsensical answers, divergence, and other pathologies that complex computational systems are prone to. More importantly, the experts make major discontinuous design decisions, or go “outside the box” by stretching parameter ranges or even adding new computational capabilities, making the ICE method a true design tool, not just a non-linear equation solver. ICE Model Each session was broken down into three segments: pre-processing, design, and post-processing. Customer inputs, payload design, and mission objectives were decided by an Architecture chair during pre-processing. These inputs were fed to the design team and were used to develop a point design. Finally, cost was estimated during the post-processing segment. Ten ICEMaker modules were developed, with each module representing a different spacecraft subsystem or discipline. The six main modules were Mission, Systems, Propulsion, Link, Configuration, and Power. Each sheet performed all the calculations necessary to design its specific subsystem based on the inputs provided to it. The models were developed using first principles whenever possible, but rules-of-thumb based on current technology were also used to reduce complexity and coding time. These sheets were electronically linked through the ICEMaker server and interacted throughout a design session sharing information and updating each other of changes to the design made by the individual chairs. The ICEMaker server works primarily with Microsoft Excel® spreadsheets. This work also made innovative use of a new software tool (Oculus CO®) that was used to link routines written in Mathworks Matlab® and a parametric solid geometry model done in Solidworks® to the spreadsheets. Several key simplifying assumptions were made. First, the sheets were only required to handle one vehicle per